stm32f103驱动SHT20( I2C )

以下为SHT10的参考资料：STM32 SHT10温湿度传感器的信号采集  SHT20技术手册

首先讲讲SHT10这款温室度传感器。SHT1x（包括SHT10,SHT11和SHT15）属于Sersirion温湿度传感器家族中的贴片封装系列。更之前我讲过的DHT11这款温湿度传感器相比，体积小了许多，特别适合用于产品中。SHT10温湿度传感器包括一个电容性聚合体测湿敏感元件、一个用能隙材料制成的测温元件（文绉绉的），传感器内部有一个精度高达14为位的A/D转换器，适应串行接口电路实现无缝连接。该产品具有品质卓越、响应速度速度快，抗干扰能力强、性价比高等优点。

1、接口定义：

SHT10的接口定义如下图所示：

如上图所示，1脚为GND，4脚为VDD。它的供电电压范围为2.4~5.5V，建议的电压为3.3V，在电源引脚(VDD、GND)之间必须加上一个0.1uf的电容，应于去耦滤波用。它的2脚DATA为数据引脚，3脚SCK为时钟控制引脚，没有发现这两个引脚很像IIC所使用的引脚功能？没错，这个传感器确实可以认为是IIC接口，但是又有却别。该传感器不能按照IIC的协议编址，但是，如果IIC总线上没有挂接别的元件，传感器可以直接连到IIC总线上，但是单片机必须按照传感器的协议工作。传感器与单片机的接线如下图所示：

说明： 应用STM32驱动SHT20

I2C 部分驱动参考：http://www.openedv.com/forum.php?mod=viewthread&tid=100058

测试结果：

sht2x.c

/*

This source code and any compilation or derivative thereof is the proprietary

information of mingfei.tang Lighting Holding B.V. and is confidential in nature.

Under no circumstances is this software to be combined with any

Open Source Software in any way or placed under an Open Source License

of any type without the express written permission of mingfei.tang Holding B.V.

*/

/*******************************************************************************

* EXPORT INCLUDE FILES

*******************************************************************************/

#include "I2C.h"

#include "Stm32hal.h"

/*******************************************************************************

* LOCAL INCLUDE FILES

*******************************************************************************/

#include "sht2x.h"

/******************************************************************************

* LOCAL MACROS AND DEFINITIONS

******************************************************************************/

#define I2C_ADDRESS (0x40 << 1)

#define POLY  0x131;  //P(x)=x^8+x^5+x^4+1 = 100110001

/******************************************************************************

* LOCAL FUNCTION DECLARATIONS

******************************************************************************/

static void i2c_Delay(uint16_t value );

static uint8_t sht2xdrv_CheckCrc(uint8_t data[], uint8_t nbrOfBytes, uint8_t checksum);

static uint8_t sht2xdrv_CheckOk(void);

static int32_t sht2xdrv_CalcTemperatureC(uint16_t u16sT);

static int32_t sht2xdrv_CalcRH(uint16_t u16sRH);

static void i2c_Delay(uint16_t value )

{

    uint16_t i;

    for (i = 0; i < value; i++);

}

static uint8_t sht2xdrv_CheckCrc(uint8_t data[], uint8_t nbrOfBytes, uint8_t checksum)

{

    uint8_t res = 0;

    uint8_t crc = 0;

    uint8_t byteCtr;

    //calculates 8-Bit checksum with given polynomial

    for (byteCtr = 0; byteCtr < nbrOfBytes; ++byteCtr)

    {

      crc ^= (data[byteCtr]);

      for (uint8_t bit = 8; bit > 0; --bit)

      {

        if (crc & 0x80)

        {

          crc = (crc << 1) ^ POLY;

        }

        else

        {

          crc = (crc << 1);

        }

      }

    }

    if (crc != checksum)

    {

      res = 1;

    }

    return res;

}

static uint8_t sht2xdrv_CheckOk(void)

{

    if (i2c_CheckDevice( I2C_ADDRESS ) == 0)

    {

         /* sensor is online*/

            return 1;

    }

    else

    {

          /* fail: send stop */

            i2c_Stop();

            return 0;

    }

}

static uint8_t sht2xdrv_ReadUserRegister( uint8_t *pRegisterValue )

{

    uint8_t ret = SHT2x_STATUS_OK;

    uint8_t cmd = USER_REG_R;

    i2c_Start();

    i2c_SendByte( I2C_ADDRESS | I2C_WR );  // Device address 

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    }

    i2c_SendByte( cmd);

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    }

    //Read 

    i2c_Start();

    i2c_SendByte(I2C_ADDRESS | I2C_RD);

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    } 

    *pRegisterValue = i2c_ReadByte();

    i2c_NAck();

    i2c_Stop();

    return ret;

cmd_fail:    

    i2c_Stop();

    ret = SHT2x_STATUS_ERR_BAD_DATA;

    return ret;

}

static int32_t sht2xdrv_CalcTemperatureC(uint16_t u16sT)

{

  int32_t temperatureC;       // variable for result

  u16sT &= ~0x0003;           // clear bits [1..0] (status bits)

  /*

     * Formula T = -46.85 + 175.72 * ST / 2^16 from data sheet 6.2,

     * optimized for integer fixed point (3 digits) arithmetic

  */

  temperatureC = (((uint32_t)17572 * u16sT) >> 16) - 4685;

  return (int32_t)temperatureC;

}

static int32_t sht2xdrv_CalcRH(uint16_t u16sRH)

{

  uint32_t humidityRH;       // variable for result

  u16sRH &= ~0x0003;          // clear bits [1..0] (status bits)

  /*

     * Formula RH = -6 + 125 * SRH / 2^16 from data sheet 6.1,

     * optimized for integer fixed point (3 digits) arithmetic

  */

  humidityRH = (((uint32_t)12500 * u16sRH) >> 16) - 600;

  return (int32_t)humidityRH;

}

uint8_t  sht2xdrv_GetTemp( int32_t *pMeasurand )

{

    uint8_t ret = SHT2x_STATUS_OK;

    uint8_t checksum;                   //checksum

    uint16_t rawdata;

    uint8_t cmd = TRIG_T_MEASUREMENT_HM;

    uint8_t data[3] = {0, 0, 0};        //data array for checksum v

    i2c_Start();

    i2c_SendByte( I2C_ADDRESS | I2C_WR );  // Device address 

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    }

    i2c_Delay( 100 );

    i2c_SendByte( cmd);

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    }

    //Read 

    i2c_Start();

    i2c_SendByte(I2C_ADDRESS | I2C_RD);

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    }

    HAL_Delay( 70 );

    data[0] = i2c_ReadByte();

    i2c_Ack();        

    data[1] = i2c_ReadByte();

    i2c_Ack();        

    data[2] = i2c_ReadByte();

    i2c_NAck();

    i2c_Stop();

    rawdata = ((uint16_t)data[0] << 8) | data[1];

    checksum = data[2];

    ret = sht2xdrv_CheckCrc(data, 2, checksum);   

    if (ret != SHT2x_STATUS_OK)

    {

        return ret;

    }

    *pMeasurand = sht2xdrv_CalcTemperatureC(rawdata);

cmd_fail: 

    i2c_Stop();

    return ret;

}

/******************************************************************************

* EXPORTED FUNCTIONS

******************************************************************************/

uint8_t  sht2xdrv_GetRH( int32_t *pMeasurand )

{

    uint8_t ret = SHT2x_STATUS_OK;

    uint8_t checksum;   //checksum

    uint16_t rawdata;

    uint8_t cmd = TRIG_RH_MEASUREMENT_POLL;

    uint8_t data[3] = {0, 0, 0}; //data array for checksum v

    i2c_Start();

    i2c_SendByte( I2C_ADDRESS | I2C_WR );  // Device address 

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    }

    i2c_SendByte( cmd);

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    }

    //Read 

    i2c_Start();

    HAL_Delay( 100 );

    i2c_SendByte(I2C_ADDRESS | I2C_RD);

    if (i2c_WaitAck() != 0)

    {

        goto cmd_fail;

    }

    HAL_Delay( 100 );

    data[0] = i2c_ReadByte();

    i2c_Ack();        

    data[1] = i2c_ReadByte();

    i2c_Ack();        

    data[2] = i2c_ReadByte();

    i2c_NAck();

    i2c_Stop();

    rawdata = ((uint16_t)data[0] << 8) | data[1];

    checksum = data[2];

    ret = sht2xdrv_CheckCrc(data, 2, checksum);   

    if (ret != SHT2x_STATUS_OK)

    {

        return ret;

    }

    *pMeasurand = sht2xdrv_CalcRH(rawdata);

cmd_fail: 

    i2c_Stop();

    return ret;

}

uint8_t  sht2xdrv_ResetSht2x( void )